Jwakil.  Malsal would be the expert to answer that question.. I will ask him  tomorrow..

PhatHeadDonnie, my question was: is there a throttle position sensor in addition to the stepper motor that controls idle or would kill the engine if no throttle applied.

jwakil.  yes there is idle motor.. I got mine last time from Burlen Fuel Systems in England.. I finally just bought 1.5 SU carb new also from Burlen and did away with the SPI.. Not quite as much power. but does Not cut off going 75 MPH on the interstate anymore..  I  also have had the SPI and MPIs throttle bodies rebuilt at MiniSpares.com  also in england.. was about $440 per re build

My 1992 SPI mini ran great for a long time and suddenly died on me.  It will start right up, after two seconds dies.  I can keep it running by applying gas pedal, and it seems to run fairly smooth, however as soon as I take the foot of the gas pedal RPMs go straight to zero and dies.  So far I have:
-Checked vacuum lines from intake manifold to fuel trap and ECU
-Checked fuse and inertia cuttoff switch for fuel pump.  (Cuttoff switch is already bypassed and fuse is fine but since car runs with throttle applied fuel pump is probably not the problem anyway).

What else can I look at?
Is there a throttle position sensor, or is the stepper motor for idle the only control mechanism for idle?
How does one get the error codes, do I need a special reader?  I don't see any diagnostic connector.